The leadoff question that would completely negate this thread is whether Blazing Shield counts as "casting or channeling".
Light of Cyrodiil 5 armor set bonus: "While casting or channeling a spell, incoming damage is reduced by 25%."

Blazing Shield can be 'popped' by cc as shown in this (old) video I made back when my (old) build was featured: Blazing Shield Testing
This makes me think that it counts as 'casting or channeling' because, clearly, it can be interrupted/triggered before the full duration (even if it is because the shield is depleted)! Does anyone have counter-evidence to this? Can an avid tester test this for me please and see if the set's mitigation works in combo with Blazing Shield? Thanks!

'Wtf? Why would you want to reduce incoming damage when that's how you deal damage with BS?' You're right, this is crazy, but I WANT TO KNOW! I'm not a damage dealer - I'm a tank/healer And the other stats on the set are great for my magicka needs as well. Blazing Shield is more about survival and mind-games with me - the damage is just icing. This could be a sweet PvE tank combo. But it's a Cyrodiil set, and that's where I live - so I put it in the PvP section